Food begins to fail from the time it is harvested or slaughtered. Failure begins with an enzyme action that affects bacterial growth as food cells die. Food temperatures between 40° F. and 140° F. are known as “the food danger zone”. Although in many cases spoiled food can be identified by smell, taste and appearance, harmful bacteria such as salmonella and E. coli occur without any physical signs, smells or tastes whatsoever.
Bacteria are really small, and it takes a lot of them to make us sick. To overcome food sicknesses, we merely have to stop multiplying or at least slow bacterial growth down. One method of slowing down spoilage is cold temperatures which retard bacterial growth. Cold temperature methods include refrigeration between 32° F. and 40° F. and freezing at 0° F.
One problem with cold temperature methods is that freezers and refrigerators are subject to mechanical and electric power failures. Power outages can occur several times when an owner is away from home. After power is restored, a freezer can function normally without leaving evidence that food has spoiled leaving them subject to bacterial infections. A need exists for informing returning owners that a freezer has failed and their food is not fit to eat. It can also be used to indicate that their food is not fit to eat in a refrigerator that has failed.